So sánh: 2018/2019 và 2019/2020.
Giải thích
\[1 - \frac{{2018}}{{2019}} = \frac{1}{{2019}}\]
\[1 - \frac{{2019}}{{2020}} = \frac{1}{{2020}}\]
Ta có 2019 < 2020, suy ra \[\frac{1}{{2019}} > \frac{1}{{2020}}\]
Suy ra \[ - \frac{1}{{2019}} < - \frac{1}{{2020}}\]
Suy ra \[1 - \frac{1}{{2019}} < 1 - \frac{1}{{2020}}\]
Vậy \[\frac{{2018}}{{2019}} < \frac{{2019}}{{2020}}\].